All participants undergo fMRI. This test uses a strong magnetic field and radio waves to obtain images of body organs and tissues. The subject lies on a table that is moved into the scanner (a metal cylinder), wearing earplugs to muffle loud knocking and thumping sounds that occur during the scanning process. The procedure lasts about 90 minutes, during which time the patient is asked to lie still for 10-15 minutes at a time. During the procedure, subjects are asked to perform some tasks, including writing, tapping with their hand, and drawing in a zigzag motion. Each task is performed using the right hand, left hand and right foot.